Slurry burner



July 23, 1968 E. L. DAMAN ETAL SLURRY BURNER Filed Aug. 24, 1964 2Sheets-Sheet 1 I SEPARATOR (O/IP55 OECA/YTER pmer- ALLY OR/fD" FINE FUELMIX AIR BOX ATTORNEY United States Patent 3,393,650 SLURRY BURNER ErnestL. Daman, 180 Lincoln Road, Westfield, NJ. 07090, and Gilbert C.Whitney, Jr., 266 Main St. and Jay Lynn Clark, RED. 2, both ofDansville, N.Y.

Filed Aug. 24, 1964, Ser. No. 391,566 7 Claims. (Cl. 1107) ABSTRACT OFTHE DISCLOSURE The transmission of coal in pipe lines as a water slurryfor power plant use is becoming economically feasible.

Present methods for burning wet coal depend upon drying the wet coalbefore the entry of the coal into a burner for combustion. The presentinvention is designed to eliminate this drying operation.

Therefore, it is an object of the present invention to provide acombustion system and coal burner which are capable of utilizing andburning wet coal.

According to the present invention, an economical system for burningslurry mixtures of coal and 'water includes the following concepts. Theslurry mixture is first separated into an approximately 20% moisturecoarse coal stream and a slurry stream of fine coal and the latter isdecanted to an approximately 50% moisture content -fine coal slurry. Thereduced moisture content slurry is injected into an oil and slurryburner tip located in the central portion of an otherwise conventionalburner which has, as its main fuel supply, the dry coal now pulverized.The oil is used to light off the pulverized coal which in turncontinuously maintains combustion of the reduced moisture contentslurry.

The invention and advantages will become apparent from a description ofa preferred embodiment of the present invention, as shown in thedrawings wherein:

FIGURE 1 shows a general flow diagram of the combined oil and slurryburner system.

FIGURE 2 is an enlarged transverse sectional view of the central portionof the burner of FIGURE 1 taken along the line 22 of FIGURE 3.

FIGURE 3 is a side elevational view of the combined oil and slurryburner tip of FIGURE 2.

Referring now to FIGURE 1, there is shown an oil and slurry burner tip11 which is mounted within the interior of a conventional pulverizedcoal burner housing 12, for instance, of the type described in PatentNo. 2,912,942, issued to Gilbert C. Whitney and Jay L. Clark, dated Nov.17, 1959. Similar to a conventional pulverized coal burner, drypulverized fuel and air enter through the pulverized fuel and primaryair inlet 13, into outer annular passageway 14, and exit at annular endregion 15 projecting a flame into the furnace indicated by furnaceinterior wall 24. The pulverized coal entering inlet 13 is drawn frompulverizer by fan 16. Secondary intake air isprovided through air inlet17.

Coal slurry mixtures of water and coal transported from the coal fieldsto the ultimate boiler user through pipe lines indicated by 18, are sentinto a centrifuge separator 19. The centrifuge separates coarseapproximately 20% moisture coal from the slurry as received, leavingfines and water, the coal exiting from the centrifuge through conduit 20to pulverizer 15 for pulverization. It is then trans- 3,393,650 PatentedJuly 23, 1968 ported by fan 16 into the burner annular portion 14 asdescribed above.

The fine wet coal leaves separator 19 through conduit '5 to decanter 9,the latter reducing the moisture content of the fine coal toapproximately 50%. The reduced moisture coal leaves decanter 9 throughconduit 21 and enters wet slurry burner tube 22 located in the centralburner assembly 11 for burning at the hot end of tube 22. Clear water isrejected via eflluent duct 43.

Reference may now be made to FIGURES 2 and 3 for an assembly view ofportions of the burner. The wet fine coal passing through tube 22 existsthrough nozzle 23, entering the furnace through throat 27 centrallylocated in the nozzle 23. Pressurized air enters chamber 8 from airsnply conduit 25, and exits through air jet passages 28 in the nozzleinto frustoconical section 29 through equally spaced openings 42defining a circle adjacent the narrowmost portion of section 29. The airjets 28 are oriented to direct pressurized air into the frustoconicalsection 29 in three vectorial components. One component is tangential tothe circle formed by openings 28 as may be readily seen in FIG. 3. Thesecond component is in a direction parallel to the axis of thefrustoconical section, and the third component is radial to the axis ofthe frustoconical section. Together they cause a helical swirling airmovement with-in the area bounded by the frustoconical portion 29 tocause the coal passing through throat 27 to enter the furnace as anatomized spray. The wet fine coal exiting from throat 27 is caught up inthis swirling air movement becoming dispersed and spray atomized.

Oil is supplied to fuel oil tube 7 and exits through nozzle orifices 31near conventional igniter electrode shown at 32 for initially ignitingthe oil leaving orifices 31. The ignited oil provides a high temperaturesecondary ignition system for igniting the dry pulverized fuel leavingannular portion 14 (as shown in FIGURE 1) at hot end 15 as accomplishedin a conventional pulverized burner. After ignition is sufficientlyestablished in the dry pulverized fuel so as to be self sustaining, theoil supply is turned off.

The burning of the pulverized fuel flame provides a continuous primaryignition or heat source and continuously ignites and causes the wet fineslurry spray from nozzle 23 to burn, the latter being unable to maintainby itself stable combustion. Burning of the slurry is maintained bysustained ignition, and the self sustaining combustion of the drypulverized fuel provides the source required. The atomizing action ofnozzle 23 provides sufficient slurry surface area to promote completeevaporation of the water in the slurry and subsequent combustion of thefine dry coal in the slurry.

Assembly or housing 11 having hot end -wall 39 and cold end wall 41 isarranged for convenient adaptation to existing conventional burners. Airtight tapered pipe threads are provided to seal tubes 22 and 7 tonozzles 23 and 40 respectively. Atomizer nozzle 23 and tube 22 are heldin place against hot end wall 39 by spanner nut 38 at the cold end, thelatter sealed by gasket 37 adjacent the inlet end of the slurry tube.Gasket 36 is provided to seal the hot end of air chamber 8 betweennozzle 23 and hot end wall 39. Oil burner nozzle 40 is connected to oiltube 7 via coupling 6 which is welded to wall 39. At the cold end, thetube 7 is sealed in place by gasket 37a against cold end wall 41 andspanner nut 38a.

Although not restricted thereto the present invention was found tooperate successfully under the following conditions. A slurry mixture ofcoal in semi-ground for-m mixed with water in the proportion ofapproximately 60% coal to 40% water by weight was utilized. The coalcontent of the slurry mixture contained coarse and fine coal in thefollowing percentages: pass through 3 a No. 19 U.S. standard sieve, 94%through a No. 16 screen, 63% through a No. 50 screen, 49% through a No.100 screen, 40% through a No. 200 screen, and 33% through a No. 325screen.

This mixture is initially sent to the separator 9 and is separated intoa fine wet slurry eflluent and a coarse coal stream. The fine wet slurryleaving the separator through line contains 90% water and 10% fine coal.The fine coal consists approximately of 100% through a No. 100 screen,95% through a No. 200 screen and 90% through a No. 325 screen. Theremainder of the coal, i.e., the coarser coal leaving the separatorthrough line 20, contains 18% water. The remainder is passed to thepulverizer where it is dried by hot air passing through the pulverizerand is pulverized sufficientlyfor use in the type burner shown in U.S.Patent No. 2,912,942.

The percentage of fine coal passing through line 5 relative the coarsecoal passing through line 20 is 5% and 95 respectively. The fine Wetslurry is sent to decanter 9 which reduces the moisture content oftheefiluent to approximately 50% water to 50% fine coal. This mixture isthen passed directly into the slurry burner tube 22 at pressures fromapproximately 25 to 100 p.s.i. so that the velocity of the slurry in thetube 22 is about 10 to 20 feet per second.

The diameter of the nozzle throat 27 is inch and the frustoconicalsection forms a 60 angle of rotation with the frustoconical axis. Thenozzle 23 of this embodiment contains 12 jet channels, sloped at 30 withrespect to the axis of the nozzle to intersect with the axis of thenozzle at inch from the exposed front face of the nozzle (FIGURE 2), andangled so as to be tangential to the outline of the throat 27 as shownin FIG- URE 1. The jet openings are drilled to .082 inch. The nozzle 23is centrally placed in a conventional burner of the type described inPatent No. 2,912,942.

Compressed air under pressures of about 70 to 80 p.s.i., for the jetchannels, is found suitable to atomize the slurry passing into thecenter of the nozzle.

Where desirable, a separate supply of dry pulverized fuel may be used asan igniter for the wet fines instead of taking it from the originalslurry mixture.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangements of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

1. A burner for burning a slurry mixture of coal and water including anatomizer nozzle for atomizing said slurry mixture of coal and water,said atomizer nozzle comprising a source of pressurized air,

a nozzle tip having a passageway and an outlet portion for exiting theslurry from the passageway, said outlet portion forming a frustoconicalsection having an axis, the section narrowing up to the passageway, thepassageway being circular in cross section,

a multiplicity of jet channels communicating with the source ofpressurized air and the frustoconical section at equally spacedpositions around the periphery of the frustoconical section, saidchannels each oriented to direct pressurized air into the frustoconicalsection in a direction having a component parallel to the axis of thesection and a component tangential to a circle, the circle defined bythe intersection of a plane perpendicular to the frustoconical axis andthe frustoconical section, at each position of communication of thechannels with the frustoconical section, each tangential component beingin the same direction of rotation relative said circle associatedtherewith, so that a helical swirling current of air disperses and exitswith the slurry passingthrough the nozzle tip. 7 H ,7 I

2. A burner for burning a slurry mixture of coal and water including anatomizer nozzle for atomizing .said slurry mixture of coal and water,said atomizer nozzle comprising a source of pressurized air, v I

a nozzle tip having a passageway and an outlet, portion for exiting theslurry from the passageway, said outlet portion forming a frustoconicalsection having an axis, the section-narrowing up to the passageway, thepassageway being circular in cross section,

a multiplicity of jet channels communicating with the source ofpressurized air and the frustoconical section at equally spacedpositions defining a circle adjacent the passageway, coaxial andperpendicular to the axis of the section,

said channels each oriented to direct pressurized air into thefrustoconical section in a direction having a component parallel to theaxis of thesection and a component tangential to the circle, eachtangential component being in the same direction of rotation relativethe circle, so that a helical swirling current of air disperses andexits 'with the slurry pass ing therethrough.

3. A burner according to claim 2 wherein said channels are furtheroriented to have a component radial to the axis of this section.

4. A burner for burning slurry mixtures of fine coal and water,comprising,

a slurry tube for passing slurry therethrough,

means for supplying slurry to one end of the slurry tube, an atomizernozzle at theopposite end of the slurry tube for atomizing the slurrypassing therethrough into a fine spray,

pulverizing means for supplying a source of dry pulverized coal to thevicinity of the nozzle for burning the slurry spray when the drypulverized coal is burning,

means for supplying an ignition fuel in the vicinity of the drypulverized coal for igniting the dry pulverized coal,

means to ignite the ignition fuel,

said atomizer nozzle further comprising,

a source of pressurized air,

a nozzle tip having a passageway and an outlet portion for exiting theslurry from the passageway, said outlet portion forming a frustoconicalsection having an axis, the section narrowing adjacent the passageway,the passageway being circular in cross section,

a multiplicity of jet channels communicating with the source ofpressurized air and the frustoconical section at equally spacedpositions defining a circle which is adjacent the narrowmost portion ofthe section, coaxial and perpendicular to the axis of the section,

said channels oriented to direct pressurized air into the frustoconicalsection ina direction having a component parallel to the axis of: thesection and a component tangential to the circle so that a helicalswirling current of air-disperses and exits with the slurry passingtherethrough.

5. A burner of claim 4, said means for supplying an ignition fuelcomprising,

an oil tube for passing oil therethrough, means for supplying oil to oneend of the oil tube, an oil nozzle at the other end of the oil tube forpassing a stream of oil therefrom, means for igniting the oil, the oiltube oriented so that the stream of oil passing from said oil nozzle isin the vicinity of the dry pulverized coal so that it ignites the drypulverized coal when the oil is ignited.

6 A burner for burning a slurry mixture of fine coal and water,comprising,

a frustoconical shaped annular hollow body having an inlet and anoutlet, a volute shaped inlet section having an inlet for receiving amixture of pulverized fuel and air and having an outlet, said voluteoutlet being in communication with said main body inlet to pass saidmixture of pulverized fuel and air tangentially into said body inlet forproviding a helicoidal stream of pulverized fuel flowing through saidbody,

means for continuously dispersing said helicoidal stream of pulverizedfuel and uniformly distributing the pulverized fuel across the flow areaof the body outlet,

an elongated inner housing concentrically disposed within the hollowbody,

an elongated slurry tube for passing slurry therethrough having an inletend and outlet end mounted lengthwise within the housing with the outletend adjacent the dispersing stream of pulverized fuel,

means for sluppying a slurry mixture of fine coal and water to the inletend of the slurry tube,

.an atomizer nozzle at the outlet end of the slurry tube for atomizingthe slurry passing therethrough,

an elongated ignition fuel tube disposed within the housing parallel tothe slurry tube and having an inlet end and an outlet end adjacent theslurry tube outlet end,

means for supplying an ignition fuel to the inlet end of the ignitionfuel tube,

a fuel nozzle located at the outlet end of the ignition tube for passinga stream of ignition fuel therefrom in the vicinity of the drypulverized coal for igniting the dry pulverized coal, and

means mounted within the hollow body adjacent the housing to ignite theignition fuel.

7. A burner of claim 6, further comprising, means for passingpressurized air into the housing, said atomizer nozzle comprising,

a nozzle tip having a passageway and an outlet portion for exiting theslurry from the passageway, said outlet portion forming a frustoconicalsection having an axis, the frustoconical section narrowing adjacent thepassageway, the passageway being circular in cross section, and

a multiplicity of jet channels communicating with the pressurized air inthe housing and with the frustoconical section at equally spacedpositions defining a circle which is adjacent the narrowmost portion ofthe section, coaxial and perpendicular to the axis of the section, saidchannels oriented to direct pressurized air into the frustoconicalsection in a direction having a component parallel to the axis of thesection and a component tangential to the circle, each tangentialcomponent being the same direction of rotation relative the circle, sothat a helical swirling current of air disperses and exists with theslurry passing therethrough.

References Cited UNITED STATES PATENTS 2,535,730 12/1950 Gadret 1107 X2,716,002 8/1955 Craig 110106 X 3,002,472 10/1961 Miller 1101063,124,086 3/1964- Sage et al. 1107 3,229,650 1/1966 Reichl 11073,229,651 1/1966 Wasp 1107 CHARLES J. MYHRE, Primary Examiner.

